Friday, February 01, 2019

AHA: Flu, Flu-like Illnesses Linked to Increased Risk of Stroke, Neck Artery Tears


Two decades ago, a study looked at the rate of heart attacks in the United States, and found that Acute Myocardial Infarctions (AMIs) run as much 53% higher during the winter months than than during the summer.
Seasonal distribution of acute myocardial infarction in the second National Registry of Myocardial Infarction.
Spencer FA, Goldberg RJ, Becker RC, Gore JM. 
Cold weather combined with strenuous physical activity (like clearing snow from sidewalks) have often been blamed for this increase, but even in balmy Southern California, studies have shown a 33% increase in heart attacks over the holidays (see below). 
When Throughout the Year Is Coronary Death Most Likely to Occur?
A 12-Year Population-Based Analysis of More Than 220 000 Cases
Robert A. Kloner, MD, PhD; W. Kenneth Poole, PhD; Rebecca L. Perritt, MS
Non-climate related factors – such as over indulgence in food and alcohol, diminished activity levels, forgetting to take prescription medicines, and combined holiday stressors like shopping, running up debt, traveling, meal preparation, and the angst that comes from dysfunctional family gatherings are all likely contributors to this yearly spike.  

But increasingly influenza and other respiratory infections have been linked to this seasonal increase in heart attacks and strokes.  A few recent studies include:
Chest: Flu Vaccine Reduces Severe Outcomes Among Hospitalized Patients With COPD
NFID: Chronic Health Problems & The Flu
Eur. Resp.J.: Influenza & Pneumonia Infections Increase Risk Of Heart Attack and Stroke
NEJM: Acute Myocardial Infarction After Laboratory-Confirmed Influenza Infection
Int. Med. J.: Triggering Of Acute M.I. By Respiratory Infection
This week the American Heart Association has published a press release on two studies - to be presented next week at the American Stroke Association’s International Stroke Conference - that link respiratory infections like influenza to as much as a 40% increased risk of stroke.

Flu, flu-like illnesses linked to increased risk of stroke, neck artery tears
American Stroke Association News Release Combo – Abstract 189, Session A36 and Poster WMP49, Session MP5

January 30, 2019 Categories: Scientific Conferences & Meetings, Stroke News

Combo Study Highlights:

  • Flu-like illnesses are associated with an increased risk of stroke and neck artery dissection.
  • The risk of stroke and neck artery dissections are greatest within a month of a flu-like illness.
Embargoed until 4 a.m. CT/5 a.m. ET, Wednesday, Jan. 30, 2019

DALLAS, Jan. 30, 2019 — Flu-like illnesses are linked to an increased risk of stroke and neck artery dissections, according to two preliminary research studies to be presented in Honolulu at the American Stroke Association’s International Stroke Conference 2019, a world premier meeting for researchers and clinicians dedicated to the science and treatment of cerebrovascular disease.

In the first study (abstract 189), researchers found that having a flu-like illness increased the odds of having a stroke by nearly 40 percent over the next 15 days. This increased risk remained up to one year.

Researchers estimated the odds of hospitalization for ischemic stroke after hospitalization for a flu-like illness. They identified 30,912 patients who suffered an ischemic stroke in 2014 in a review of patient records from the 2012-2014 inpatient and outpatient New York Statewide Planning and Research Cooperative System (SPARCS). Study participants were 49 percent male, 20 percent black, 84 percent urban and average age 71.9 years old.

Researchers compared each patient’s “case window” – the time preceding stroke – to the time window for a set of control periods using the same dates from the previous two years. The analyses were stratified by urban and rural status based on residential zip code, sex and race.

“We were expecting to see differences in the flu-stroke association between rural and urban areas. Instead we found the association between flu-like illness and stroke was similar between people living in rural and urban areas, as well as for men and women, and among racial groups,” said Amelia K. Boehme, Ph.D., the study’s lead author and assistant professor of epidemiology in neurology for Vagelos College of Physicians and Surgeons at Columbia University in New York City.

There are many proposed mechanisms behind the flu-stroke link, but no definitive reason has been described to explain the association. Researchers suspect it could be due to inflammation caused by the infection.

In a second study (poster WMP49) from the same institution, researchers found an increased risk of tearing neck arteries within one month of battling a flu-like illness. Non-traumatic cervical artery dissection is a leading cause of ischemic stroke in patients 15- to 45-years old.

Researchers reviewed 3,861 cases (average age 52 years, 55 percent men) of first non-traumatic cervical artery dissection within the New York State Department of Health Statewide Planning and Research Cooperative System (2006-2014). They found 1,736 instances of flu-like illness and 113 of influenza during the three years preceding cervical artery dissection.

Patients were more likely to suffer a flu-like illness within 30 days prior to cervical artery dissection compared to the same time one and two years before.

“Our results suggest that the risk of dissection fades over time after the flu. This trend indicates that flu-like illnesses may indeed trigger dissection,” said Madeleine Hunter, B.A., the study’s lead author and a second-year medical student at Vagelos College of Physicians and Surgeons at Columbia University in New York City.

Hunter said the strength of the research comes from using a dataset collected by the New York State Department of Health, which records diagnoses in non-federal, state-licensed facilities, enabling the researchers to amass a large sample size.

“An important limitation of using an administrative dataset is that we had to rely on billing codes to determine who had cervical artery dissections, influenza and flu-like illnesses. If a diagnosis was not coded or miscoded, we could not capture it,” Hunter said.

Co-authors for abstract 189 are: Trevor Alvord, M.P.H.; Erin R. Kulick, Ph.D., M.P.H.; Michelle Canning, M.P.H.; and Mitchell S. Elkind, M.D., M.S.

Co-authors for poster WMP49 are: Yeseon P. Moon, M.S.; Amelia K. Boehme, Ph.D.; Erin R. Kulick, Ph.D., M.P.H.; Trevor Alvord, M.P.H.; and Mitchell S. Elkind, M.D., M.S.
Boehme’s study was funded by the National Institutes of Health (NIH) National Institute of Neurological Disorders and Stroke and NIH National Institute on Minority Health and Health Disparities. Hunter’s study was funded by National Institutes of Health and the Giordano Family Foundation.

Note: Scientific presentation for 189 is 9:09 a.m. HT/2:09 p.m. ET, Friday, Feb. 8, 2019.

Scientific presentation for WMP49 is 5:30 p.m. HT/10:30 p.m. ET, Wednesday, Feb. 6, 2019.
While the flu vaccine isn't an ironclad guarantee of avoiding infection, most years it provides moderately good protection against circulating influenza viruses.  And for those who are vaccinated - but still get the flu - they are less likely to have a severe bout.

This from the CDC:
Flu Vaccine Reduces Serious Flu Outcomes

Flu vaccination has been shown to reduce flu illnesses and more serious flu outcomes that can result in hospitalization or even death in older people. For example, a 2017 study showed that flu vaccination reduced deaths, intensive care unit (ICU) admissions, ICU length of stay, and overall duration of hospitalization among hospitalized flu patients; with the greatest benefits being observed among people 65 years of age and older.
When you factor in a potential reduction in the risk of a having a devastating stroke or heart attack - for this rapidly ageing baby boomer -  getting the flu shot every year seems like pretty cheap insurance.

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